Apparatus for utilizing heat energy.



H. A. HUMPHBEY. APPARATUS FOR UTILIZING HEAT ENERGY.

APPLICATION FXLED APR. 7, 19M.

Patented June 5,1917.

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WITfI'ESSES ATTORNEY.

H. A. HUMPHREY.

APPARATUS FOR UTILiZING HEAT ENERGY.

APPLICATION FILED APR. 7, 1914.

Patented June 5, 1917.

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H. A. HUMPHREY.

APPARATUS FOR UTILIZING HEAT ENERGY.

APPLICATION FILED APR. 7, 1914.

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APPARATUS FOR UTILIZING HEAT ENERGY.

APPLICATION FILED APR. 7, I914;

Patented June 5, 1917.

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H. A. HUMPHREY.

APPARATUS FOR UTILIZING HEAT ENERGY.

APPLICATION FILED APR. 7, I914.

Patented June 5, 1917.

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H. A. HUMPHREY.

APPARATUS FOR UTILIZING HEAT ENERGY.

APPLICATION FILED APR. 7. 1914.

1,828,444. Patented June 5, 191?.

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APPARATUS FOR UTILIZING HEAT ENERGY.

APPLICATION FILED APR. 1, 1914.

Patented J we 5, 1917.

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Nit! PATENT OFFICE.

HERBERT ALFRED HUMPHREY, OF LONDON, ENGLAND, ASSIGNOR TO I-IUMPHREY GAS PUMP COMPANY, A CORPORATION OF NEW YORK.

APPARATUS FOR UTILIZING HEAT ENERGY.

Original application filed July 17, 1908.

pending application filed July 17, 1908, present apfiierial No. ll hOGl of which the plication is a division.

le'ferring to the drawings, which illus-' trate merely by way of example such apparatus- Figure 1 is a diagrammatic vertical sec-' tion. I I a I Fig. 2 is a similar view of a modified form of apparatus. I

Fig. 3 is a similar view of another medltied form.

Fig. 4t is a similar view of another modificd form. a

. Figs. 5. 6, 7, 8 and 9 are similar views showing further modifications.

Fig. 10 is a diagrammatic vertical section on a reduced scale showing further modifications.

Fig. 11 is a diagrammatic plan view.

i-"ig. 12 is a vertical section of a device For controlling the pressure at the a r delivery. I

Fig. 13 is a vertical section 011 a measuring device for combustible charges.

i-Fig. 14L is a vertical section of a device for controlling the amount oi combustible charge admitted at each cycle with relation to the amount of compressed air required.

Fig. is a vertical section of a device :iior varying the effective volume of the combustion chamber orthe compressor chamber. Fig. 116 a vertical section of the device whereby the elastiofluid compressed is separatcd from the compressing mass of fluid.

I F 17 is avertical section on a some' what enlarged scale of another modified form of apparatus wherein the combustion and compressor chambers alternate in their functions.

Fig; 18 is a vertical section on areduced Specification of Letters Patent.

Patented June 5, 1917.

Serial N05444:,Q61. Divided and this application filed April '7, 1914. Serial No. 830,262.

scale of a device showing the pump chamber at an elevation above the compressor chamber. i

Fig. 19 is a similar view showing the compressor chamber elevated above the pump chamber.

Fig. '20 is a similar view showing the features of Figs. 5, 13 and 14 combined in a single apparatus.

Similar numerals refer to similar parts hroughout the several views.

it form of theapparatus, which may be regarded as one of the simplest examples inasmuch as it does not require that there shall be either an intake or discharge of fresh liquid at each cycle, is shown in Fig. 1., in which 1 is the pump chamber and 3 the compressor chamber, connected by a liquid duct 4. In the top of chamber 1 are fitted an admission valve 5 for cumbustible mixture and an exhaust valve 6 for burnt products. In the co -pending application of Humphrey and Rusdell filed June 13, 1908 having Serial No. 438,426, are described several types of valve gear suitable for controlling the valves and applicable to the present purpose. When there is no liquid inlet valve, valve gears which in presence of such a valve are dependent thereon for their operation, may be made to depend in siinilar manner on a flexible diaphragm or piston fitted to the combustion chamber. It will be sufficient to state that whatever valve gear is used the exhaust valve opens when the ignited combustible mixture has expanded to substantially atmospheric pressure or other desired pressure, and is shut when the rising liquid has exhausted sufficient of the products of combustion. The exhaust valves may conveniently be shut by impact of the rising liquid, and remain shut until the next ignited charge expands to atmospheric pressure. The admission valve opens by suction against the action of a light spring during the period at which it is desired. to introduce the charge. In the present example the stem of the admission 'alve carries a pin 7 capable of engaging with the bell crank 8 pivoted at 9 and carrying a pin 10 for engaging in the slotted end of rod 11 attached to a pawl 12 pivoted at 13 on the compressor.

On the compressor is fitted an inlet valve 1 which opens against a light spring and may be locked in an open position by pawl 12 which when pulled to the right by spring 18 engages above the collar 17 on the stem of valve 1 1, and so keeps this valve from closing again until this pawl is released by the.motion of bell crank 8 which occurs when admission valve 5 opens. There is also fitted on the compressor a non-return outlet valve 15 controlled by a spring. In the outlet pipe there is also a valve 16 suitably supported and adapted to close on a seat just above it; this valve is so loaded, however, that the escaping air cannot close it, although the impact of the rising liquid is capable of doing so. The outlet pipe projects some distance into the compressor chamber so that the liquid rising in the chamber can drive out air until the level of the liquid reaches the level of the projecting part 19 of the pipe, but further rise of the liquid imprisons a. cushion of air in the top of the compressor chamber and causes liquid to be forced up the outlet pipe to shut valve 16 after which, all outlets being closed in the top of the compressor chamber, the imprisoned elastic cushion may be further compressed.

The action of the apparatus may now be explained. The valves being in the position shown, it may be assumed that there is a compressed combustible mixture in the top of chamber 1 above the level of the liquid and that there is a charge of air or other elastic fluid in chamber approximately at atmospheric pressure. Explosion occurs at or about maximum compression pressure; as a suitable mode of ignition, that explained in my copending application filed May 11, 1908 having Serial No. 132,171, may be adopted. The increase of pressure thus produced drives the liquid downward and outward from chamber 1 through the pipe 4: which is long enough to permit a considerable portion of the energy to be transformed into kinetic energy of the moving liquid, and causes the liquid to rise in chamber 3, thus compressing the air therein. It may be assumed that on the discharge side of valve 15 there already exists compressed air at a pressure corresponding with that at which it is desired to deliver the air so that valve 15 will not open until the pressure in chamber 3 exceeds somewhat the pressure at which the air is to be delivered, after which air will be discharged past valve 16 which remains open and past valve 15 which is opened under the action of the compressed air. According to the circumstances of the case, it may be that the level of the liquid in chamber 3 will not rise above the level of the lower projecting portion 19 of the outlet pipe; but if it does, a cushion is formed in the top of chamber 3 above this level and valve 16 is shut by impact of liquid rising in the outlet pipe, in

haust pipe toward the chamber.

which case the further rise of pressure due to the compression of the elastic cushion will for the time being keep valve 16 shut.

Returning to the consideration of chamber 1, when expansion has reached atmospheric pressure valve 6 opens and, should the movement of the liquid column not have ceased by this time, further movement of the liquid will cause air or products of combustion to be drawn back through the ex- On the column of liquid coming to rest the level of liquid in chamber 1 is at its lowest point and in chamber 3 at its highest point, and in the top of chamber 3 there is a quantity of compressed air consisting of that portion of the total charge which has not been expelled through the outlet pipe. This compressed air now forces the column of liquid downward and outward from chamber 3, thus reversing the flow and causing liquid to rise in chamber 1. There being a free opening through the exhaust valve to atmosphere, the liquid rising in chamber 1 expels the burnt products therefrom until, on attaining the level of valve 6 it shuts this valve by impact and compresses an elastic cushion in the top of chamber 1. In the meantime the energy of compression of the air contained in chamber 3 having been expended in imparting velocity to the colmum of water, the air arrives at atmospheric pressure and the continued downward motion of the liquid in the chamber 3 causes a fresh charge of air to be drawn in through valve 14 which is sucked open against the action of a light spring. When this occurs pawl 12, which previously rested against collar 17, is pulled by spring 18 and engages over the collar so that it looks the inlet valve in its open position. A point in the cycle is now reached where the column of liquid once more comes to rest and there is contained in the top of chamber 1 a compressed elastic cushion in this case consisting of burnt products, or of burnt products and air, and in chamber 3 there is air at atmospheric pressure.

The compressed elastic cushion in the top of chamber 1 'now expands, reverses the flow of liquid, and on the level of the liquid falling until atmospheric pressure is reached,

which occurs when the level is about that of valve 6, the further motion of the liquid opens the admission valve 5 against the action of its light spring and draws in a fresh combustible charge. Exhaust valve 6 cannot open because it is locked in one or other of the. manners described in said copending application Serial No. 438,4t26. The admission valve 5 in opening operates bell crank 8, rod 11, and pawl 12, and so permits the'spring of valve 14 to close the valve, thus stopping the discharge of air which was occurring as the liquid rose in chamber 3.

This arrangementinsures that the whole energy of expansion of the elastic cushion shall be utilized in giving velocity to the column of liquid until atmospheric pressure or thereabout is reached in chamber 1, after which admission valve 5 opens and valve 14 closes as described. The liquid continues to move from the pump portion toward the compressor portion until its energy is expended in forcing liquid to rise in chamber 3 and compresses the air therein, and then the liquid, having once more been brought to rest, the compressed air in chamber 3 again reverses the direction of flow, causing liquid to again rise in chamber 1 and compress the fresh combustible charge therein, which, being ignited, commences a fresh cycle.

It should be mentioned that in this. case bell crank 8, rod 11, and pawl 12 are fitted for the better regulation of the working, but are not essential thereto, as the cushion expansion energy may suihce to draw in the necessary charge although compressing air in chamber 3 throughout the cushion expansion and charging stroke in chamber 1.

The amount of the charge admitted to chamber 1 is preferably measured by a measuring device such :as that described in my co-pending application filed June 13 1908, having Serial No. {138,425, with re erence to Fig. 12, where the amount of charge drawn in is determined by the rise and fall of liquid in the measuring device.

The charge is measured not only to insure the regular working of the apparatus, but to enable the supply of combustible mixture to be cut off at the desired point so that the charge drawn in can be expanded below atmospheric pressure. In this case a partial vacuum is created in chamber 1 which assists the pressure in chamber 3 in imparting the necessary kinetic energy to the liquid to give the compression stroke in chamber 1.

In order to work the apparatus just described most advantageously the pressure at which the air or gas is delivered should not exceed a certain limit, depending upon the mean effective area of the indicator diagram taken from the power cylinder, and consequently, when other ranges of pressure are required, the apparatus is modified as will be described.

In order that the operation of the compressor may be variable in the sense that it may deliver at each cycle either a large quantity of air at relatively low pressure or a small quantity of air at relatively high pressure, the modification shown in Fig. 2 maybe adopted. Here, in addition to the parts already described and similarly numbered, chamber 3 has another pipe 20 communicating with the atmosphere and pro j'e'cting f'or a considerable distance into the chamber. This pipe contains a valve 21 'on the stem of which is a pin 22 and a collar 23 adapted to engage respectively with one arm of hell crank24 and with pawl 25. The other arm of bell crank 24 is connected by rod 26 with bell crank 8, and pawl 25 is con-- nected by rod 27 with another pawl 28, the latter being capable of engaging under 001- lar 29, but the length of rod 27 is such that the two pawls cannot both be in engagement under their respective collars.

Two springs 80 and 31 have their ends attached to rods 26 and 27 respectively in such a 'nlanner that when rod 26 moves either to the right or the left rod 27 is pulled by the springs to follow it. There is also at- 'tache'd to bell crank 8 a spring which is not shown but acts so as to render stable the extreme positions of rod 26 in a manner de scribed in said co-pending application No. 438,426. Valve 21 is intended in this case to open under its own weight, its motion being limited by a spring or stop, and to be closed by the liquid rising in pipe 20 and impinging upon the valve. When admission valve 5 opens, pin 7 engaging with bell crank 8 moves rod 26 to the left where it remains until valve 21 opens and pin 22 engages bell crank 24 to move rod 26 to the right. The action of the modified apparatus shown in. Fig. 2 may now be described. The position of the valves as shown is correct for that part of the cycle where expansion of the ignited mixturehas occurred in chamher 1 until the liquid driven downward in chamber 1 and rising in chamber 8 has 100 closed valve 21 which is locked shut by pawl 25. During the further expansion in chamher 1 the charge of air in chamber 3 is co1npressed. and a portion of it is discharged under pressure into the air delivery .pipe, but as before there remains a portion to form an elastic cushion. When the liquid comes to rest the energy of expansion of the cuhsion in chamber 3 causes the liquid to reverse its flow driving out products of combustion through exhaust valve 6, and when this valve is shut by impact giving thecushion stroke. WVhen the level of liquid fall ing in chamber 3 is such that the pressure in chamber 3 arrives at about atmospheric pressure valve 14 opens, admitting fresh air, and is locked open by pawl 12 under the action of spring 18; but valve 21 remains movement because valve 14 is open to the atmosphere but when admission valve 5 opens and so operates bell crank 8 and rod 11, pawl 12 is pulled to the left and valve 14 shuts under the action of its spring, after which the motion of the liquid is arrested by compressing air in chamber 3 and it may be expanding the charge in chamber 1, which is preferably a measured charge, below atmosphere. The charge having been drawn into chamber 1, and bell cranks 8 and 24, and rods 26 and 11 moved to theleft, valve 5 shuts, pawl 28 engages under its collar, and pawl 25 is released from under the collar of valve 21 but as there is at this time pressure in chamber 3 valves 21 and 14 remain shut. There is now a compressed cushion of air in chamber 3 and a combustible charge in chamber 1, the pressure of which may be below atmosphere, and these conditions bring about a reversal of flow of the liquid which once more falls in chamber 3 and rises in chamber 1 compressing the charge in the latter. When atmospheric pressure or thereabout is reached in chamber 3 during this part of the cycle, valve 21 will open and, by its pin engaging with bell crank 24, will reverse the position of bell cranks 24 and 8 and rod 26 so that they are brought back to the position shown. The compressed charge in chamber 1 is now ignited, and liquid flows from the pumpportion toward the compressor portion expelling air from chamber 3 through valve 21 until the liquid arrives at the level of the bottom of the pipe 20, whereupon continued rise of the liquid shuts valve 21 and the cycle is once more brought back to the point from which the operations described are repeated.

From the foregoing description it will be evident that however much air may be drawn into chamber 3 the quantity which is compressed by the working stroke occurring in chamber 1 cannot exceed the capacity of the chamber above the level of the bottom of pipe 20. Consequently by suitably adjusting this level the amount of air which undergoes compression may be varied, and the variable operation of the compressor may be thus achieved.

So far only the type of pump described in said co-pending application No. 438,426, has

been dealt with as being one of the simplest to describe, but other types of pumps as for instance that described in Patent No. 1,085,865 dated Feb. 3, 1914, are equally applicable in combination with the compressor portion to form a complete compressing apparatus. Such a combination is illustrated in Fig. 3 where 1 and 2 are the combustion chambers of the pump and 3 is the air vessel, the construction of the latter being the same as in Fig. 1. It is unnecessary to set forth in detail the cycle of operations occurring in the pump or to describe the func tions of the valve gear as they are fully dealt with in the said specification but the action of the combined apparatus may in general terms be described.

Fitted to the top of chamber 1 is an ex haust valve 33 for burnt products, which opens under the action of its own weight and closes by impact of liquid upon it, an admission valve 34 which is opened by suction against the action of a light spring which closes the valve again when the pressures on the two sides of the valve are sufliciently equalized. An exhaust valve 35 and an admission valve 36 are corresponding parts fitted to chamber 2. Pins 37 and 38 on the stems of valves 34 and 36 are adapted to engage with one end of bell cranks 39 and 40 respectively and the other ends of these bell cranks are connected together by link 41. A pin 42 is attached to one end of link 41 and engages in the slotted end of rod 11 which is attached to pawl 12 and serves a purpose similar to that of the rod bearing the same number in Fig. 1. The position of the valves shown in Fig. 3 is correct when ignition is about to occur in either of the chambers. Assuming that ignition occurs in chamber 1, there will be a cushion of burnt products in the top of chamber 2 (or a cushion containing a portion of the combustible charge if a modificationof this type of pump is being used) otherwise the chamber is full of liquid. In chamber 3 there will be a charge of air which is at atmospheric pressure. The pressure due to combustion in chamber 1 drives the liquid downward and outward from that chamber and through pipe 4 into chamber 3, driving out air past valve 14 which is at present locked open. When expansion has been carried to or about atmospheric pressure in chamber 1, exhaust valve 33 opens and in chamber 2 liquid falls, causing admission valve 36 to open and drawing in a fresh combustible charge into this chamber. This charge may be determined in quantity by measuring or throttling, and after it is drawn in the admission valve shuts under the action of its spring. Up to this stage the energy of expansion had been mostly utilized in imparting kinetic energy to the liquid, but when admission valve 36 opened its movement caused pin 38 to operate bell crank 40 rod 11 and pawl 12 thus withdrawing this pawl and permitting valve 14 to shut.

The kinetic energy then stored in the moving liquid is used to compress the charge of air at this time inclosed in chamber 3 and to deliver a portion of such charge under pressure past valve 15. There remains, how ever, sufficient air in the chamber to form the necessary elastic cushion to store the energy required to give the compression stroke. This stored energy is utilized to produce a in chamber 3 the further movement of the liquld, due to its lune-tic energy, draws a charge of air into this chamber through valve 14- which is sucked open to admit this charge and locked in its open position by pawl 12 engaging above collar 17. Thus everything is in readiness for commencing the next cycle by the ignition of the compressed combustible charge in chamber 2. The arrangement described insures that the burnt gases in either chambers 1 or 2 according to which is giving the working stroke, shall be expanded to atmosphere.

It bell cranks 39 and 10, red 11 and pawl 12 are removed. the apparatus will still work but care must be exercised in designing the proportion of the parts to insure that the burnt gases are allowed to expand to atmosphere, The main diii'erence in this case is that valve 14: is shut at the beginning of the working stroke and that air is compressed from the time that liquid begins to rise in chamber 3 instead of from the time when the burnt gases have expanded to atmospheric pressure. In either case the most advantageous working occurs when the pressure at which the air or gas is delivered does not exceed. a certain limit depending on the mean effective pressure of the ignited expanding gases. Consequently, as was explained with reference to Fig. 1, a modified arrangement is advisable when other ranges ofpressures for the compressed air are desired.

Fig. t shows such a modified arrangement in which the additional pipe 20 and valve for air 21 are shown. fitted into the top of chamber 3 as in the case of Fig. 2. There are also counterparts of the gear shown in Fig. 3, thus, bell. crank 39 has one of its arms adapted .to engage with pin 37 on the stem of valve 3a, and the other arm of this bell crank is connected by link 41 with bell crank 40. Paw]. 25 is fitted to engage under collar and is also connected by rod 4E3 with pawls 4-5 and adapted to engage under the collars i7 and 48 oi. admission valves 34 and 36 respectively. Springs 30 and 31 are connected. as shown between the two rods 49 and 4-3 so that the movement of rod 4-3 tends to follow the movement of rod 4.9. It will be seen that while link {ht is of such a length that pawls l5 and 4:6 can both be in engagement under their respective collars, pawl 25 cannot at the same time be in engagement under collar 23.

The operation of this arrangement is as follows :Assuming that there is a compressed combustible charge in chamber 1, that liquid fills chamber 2 with the exception of an elastic cushion in the top thereof, and that the valves are in the position shown. Liquid is at a relatively low level in chamber 3 and the chamber contains a charge of air. The charge in chamber 1 is now ignited. and liquid is driven downward and outward from this chamber through pipe l into chamber 3. Air is discharged past valve 21 into the atmosphere until the level of the liquid reaches the bottom of pipe 20 when liquid rising in this pipe shuts valve 21 by impact and the valve is immediately locked by pawl 25 which is brought beneath collar 23 by the tension on spring 30.

Further motion of the liquid compresses the air now inclosed in the chamber. A portion of the compressed air is discharged under pressure but there remains suflicient to form the necessary elastic cushion to store the energy for compressing the combustible charge.

As before described, when the ignited gases in chamber 1 have expanded to atmospheric pressure exhaust valve 33 opens, and liquid falls in chamber 2opening valve 36 so soon as the pawl 46 is released from under collar 48 by the movement of pawl 25 and link 43 to the right; a fresh combustible charge, preferably measured, is thus drawn in. The opening of admission valve 36 operates through pin 38 bell crank l0 and moves rod 49 to the left, thus putting tension on spring 31 so that when admission valve 36 shuts again rod 43 is urged to the left and pawl l6 engages under collar 48 and withdraws pawl 25 from under collar The liquid having come to rest a reverse flow occurs, the elastic cushion in chamber 3 expands, and liquid flows toward chambers 1 and 2 giving the usual exhaust and compression strokes. The pressure in chamber 3 continues to fall and at approximately atmospheric pressure valve 21 opens under its own weight admitting fresh air as the movement of the liquid continues. Valve 14 controlled by a light spring, may also open under suction and facilitate the intake of fresh air. When valve 21 falls link 49 is moved to the right and tension is put on spring 30 to urge rod 43 to the right. Thus at the end of this stage of the cycle there is a compressed combustible charge in chamber 2 and in chamber 3 a charge of air, and the cycle is ready to be repeated by ignition of the charge in chamber As was explained with reference to Fig. 2, by varying the length of the portion of pipe 20 that extends into chamber 3 the amount of air compressed at each cycle may be varied and consequently the energy de veloped at each cycle may be utilized in compressing a large quantity of air to a relor in compressing a atively low pressure,

to a relatively high small quantity of air pressure.

The action of the apparatus so far de scribed may be varied to some extent by varying the amount of liquid contained therein; thus, reduction of the quantity of liquid is equivalent to increasing the capacity of the chambers, and increase of the quantity of liquid is equivalent to decreas' ing the capacity of the chambers. Devices will presently be described for varying the amount of liquid to suit external conditions such as the demand for compressed air, and to compensate for liquid lost by leakage or evaporation. It will also be described presently how the liquid which reciprocates 1n the apparatus may be efficiently cooled.

Modifications of the apparatus will now be described in which at each cycle fresh liquid is admitted and rejected, and firstly in connection with Fig. 5. The pump chamber and the compressor chamber are shown in such relative position that valves and 51 for liquid, one near the pump and the other near the compressor, may be conveniently placed close together with the object that their movements may be made to control one another. tank 52 is so placed that there may be free flow of liquid to the short pipes in which these valves are situated, which pipes are continued as at 53 and 5A to communicate with the respective chambers. As before, pipe 4: connects the pump and compressor portions of the apparatus.

Assuming that the type of pump is that described in said co-pending application Serial No. 438,426, and that chamber 1 is the combustion chamber of this pump, the exhaust valve will be that shown in dotted lines, the admission valve being shown in full lines. With all the valves in the position shown and a compressed combustible charge in the top of chamber 1 and a charge of air in chamber 3, ignition occurs in chamber 1 and liquid is forced downward and outward from chamber 1 toward chamber 3. Valve 51 is normally open so that liquid can escape past it into tank 52, while kinetic energy is being imparted to the moving column of liquid. l/Vhen, however the ignited gases in chamber 1 have expanded to a suitable extent the pressure below valve 50 is equal to that above this valve, and the further expansion of these gases causes valve 50 to open against the action of spring 55 thus admitting liquid to flow into the apparatus from tank 52. Valve 50 has on its stem a pin 57 adapted to engage against one arm of rocking lever 59 which is pivoted at 60 and the other arm of whichengages against pin 58 on the stem of valve 51,-sothat the downward movement of valve 50 causes valve 51 to shut. Thus the energy of expansion of the ignited gases has been so far mainly transformed into kinetic energy of the moving column of liquid and when valve 51 shuts this kinetic energy is utilized in compressing the charge of air contained in chamber 3, some of which air is delivered under pressure past valve 15 but sufficient is retained to form an elastic cushion in which energy is stored for reversing the flow of the liquid. On reaching atmospheric pressure exhaust valve 6 is opened under the action of its own weight and when the reverse fiow occurs valve 50 is closed by the action of its spring and remains closed, owing to the pressure below the valve exceeding that above it. Liquid falls in chamber 3 and rises in chamber 1 expelling the exhaust products past exhaust valve 6 and on reaching this valve the liquid shuts it by impact and compresses the elastic cushion contained in the top of the chamber. About the time when the pressure in chamber 3 reaches that of the atmosphere valve 51 opens, also valve 1 1 is sucked open by the falling liquid and a fresh charge of air is drawn into chamber 3. Thus the level of liquid in chamber 3 tends to be maintained at the level of liquid in tank 52 and valve 141 shuts under the pressure of its own spring when the pressures are adjusted and any further movement of liquid in pipe 1 draws in fresh liquid through valve 51.

The compressed elastic cushion in the top of chamber 1 now expands. Liquid is driven downward in chamber 1 along pipe 1 and escapes past valve 51 into tank 52 until, on the pressure falling sufficiently in chamber 1 fresh combustible mixture is drawn through valve 5 until the level of liquid in chamber 1 approaches that of the liquid in tank 52. The continued movement of the column of liquid in pipe at causes valve 50 to open, thus shutting valve 51. Fresh liquid is drawn in past valve 50 and the column of liquid proceeds to compress the air in chamber 3 until the work done brings it to rest, when valve 50 shuts. Valve 5 shuts under the action of its spring after the combustible charge has been drawn in, and valve 51 remains closed under the pressure now exerted upon it. The energy stored in the elastic cushion in chamber 3 is utilized to reverse the direction of flow, so that liquid falls in chamber 3, rises in chamber 1 and compresses the combustible charge therein, and toward the ends of this flow of liquid valve 51 opens again, thus bringing all the parts once more into position for repeating "the cycle.

From the foregoing description it will be seen that the working of the apparatus last described is suitable for compressing air to high pressures inasmuch as the energy of expansion of the ignited combustible gases is at first transformed into kinetic energy of the moving liquid. and this energy maybe made to operate upon a relatively small quantity of air and thus compress this air to a high pressure. For compressing air to comparatively low pressures, the pressure of spring 55 on valve 50 is released so that this quantity of liquid rises in chamber?) than in the case last considered. The energy of expansion of the ignited gases is therefore made to compress a larger volume of air, andthat portion ofthe air which is delivered from the apparatus is delivered at a less pressure. As before, a portion of the air is'retained in chamber 3 to supply the energy to reverse the flow of liquid.

After reversal and the expansion of the air cushion in chamber 3 air is drawn into this chamber until the level of the liquid approximates to that of the liquid in tank 59, liquid meanwhile escaping past valve 50 after rising in chamber 1. The level of liquid in chamber 1 will at this time be ap' proximately the level of the liquid in tank 52, some of the products being already exhausted. The continued movement of the column of liquid in pipe 4 now causes valve 51 to open, thus closing valve 50, so that the liquid is forced to rise in chamber 1 to complete the exhaust and give the usual cushion stroke. The liquid, having come to rest, its flow is reversed under the action of the energy of the cushion in chamber 1, and the cushion expansion stroke, followed by the intake of a fresh combustible charge in this chamber, follows, during which air in chamber :3 is compressed. Before the movement of the liquid ceases valve 50 will open, while valve 51 remains shut. The liquid comes to rest, its flow is again reversed due to the pressure in chamber .3, and liquid flows downward in this chamber while the compressed air is expanding. The liquid which would otherwise rise in chamber 1 is at this time escaping through valve 50 into the tank, while the energy of expansion of the air in chamber 3 is being transformed into kinetic energy of the moving liquid: YVhen, however, theypoint in this expansion is reached at which valve 51 opens, thus shutting valve 50, the kinetic energy of the liquid is utilized in compressing the combustible charge in chamber 1. "When this kinetic energy is expended the liquid comes to rest and everything is ready for the starting of a fresh cycle by the ignition of the charge in chamber 1.

It will be seen that more liquid has entered and left chamber 3 than has entered and left chamber 1, and that the volume of air operated upon in chamber 3 is greater than in the previous case, so that the pressure at which the compressed air is delivered will be correspondingly less.

Still referring to Fig. 5, it may now be assumed that the pump is of the type in which the products of combustion are expelled and a new combustible charge drawn in by means of an oscillation of liquid which occurs between the liquid supply and the combustion chamber in a manner fully described in co-pending application filed June 13, 1908, having Serial No. 4L38A25. In this case the reciprocating liquid only makes two strokes per cycle instead of four strokes per cycle, as in the cases so far considered with reference to Fig. 5, because when expansion has occurred in chamber 1 down to that point at which valve 50 opens, liquid flows past this valve both to follow the liquid moving in the discharge pipe and also to rise in chamber 1 to expel the burnt products and shut the exhaust valve and, on the downward motion which completes its oscillation, to draw in a fresh combustible charge. This operation requires that the level of liquid in the supply tank shall be suitably adjusted and its height must be suiiicient to produce the necessary oscillation. This oscillation may be assisted by so raising the level of the liquid in the supply tank that when the oscillation occurs, the liquid rises in chamber-1 past the exhaust valve level and gives a cushion stroke followed by a cushion expansion and com bustible charging stroke, in the manner fully explained in the specification last mentioned.

As Fig. 5 is diagrammatic it is not considered necessary to show these simple modifications, but it will be understood that if the level of liquid in the tank is raised, the level of the top of chamber 3 must also be raised. The adjustment of valves 50 or 51 to give high or low pressures will be the same as before, but when the working stroke occurs in chamber 1 that portion of the air which is not discharged from chamber 3 will serve to store up the energy for giving the return flow and compressing the fresh charge chamber 1. I

Fig. 6 shows an arrangement similar to Fig. 5 but adapted to the case where the type of pump employed is that described in said Patent No. 1,085,865, in which there are two combustion chambers and in which the return flow of liquid expels the burnt products from one chamber and compresses a fresh fee combustible charge in the other chamber. 1 and 2 are the combustion chambers and 3 is the air compressor chamber, and so far as the air compressor side is concerned, the cycle is the same as that last considered. Valves 50 and 51 are also adjusted for high or low pressures and operate in the manner already described; the chief diiference from the operation described with reference to Fig. 5 lies in the fact that combustion takes place alternately in chambers 1 and 2. Several forms of valve gear for the working of the admission and exhaust valves on chambers 1 and 2 have been described in said Patent N 0, 1,085,865, and therefore no such gear is shown on the diagram.

The application of one form of apparatus mentioned in said co-pending application filed June 13, 1908, having Serial No. 438,425, to the present invention has already been described, and F ig. 7 of the accompanying drawings is added to show the application of another form of the apparatus mentioned in the said specification. The pump in this case is fitted with an automatic change over valve which alternately closes communication between the combustion chamber and the supply pipe and between the chamber and the discharge pipe, in such a manner that there is communication between the combustion chamber and the discharge pipe during compression of the combustible charge and during combustion and expansion. Communication is established between the chamber and the liquid supply during the oscillation of liquid which exhausts the products of combustion and takes in a fresh combustible charge.

It has been described in the said specification how this pump may be worked in such a manner that the quantity of liquid taken in from the supply may equal the quantity of liquid discharged back into the supply and in this form also it is applicable to the present invention. a

The pump in Fig. 7 may work with or without a cushion stroke preceding the intake of a fresh combustible charge, and to indicate this are shown two positions of the exhaust valve, one in dotted lines and one in full lines. When valve 61 is in the full-line position combustion and expansion occur in chamber 1, valve 50 is closed and valve 51 may be either open or closed according to whether the pressure at which the compressed air has to be delivered is to be relatively high or low. When expansion in chamber 1 has proceeded until thepressure on the supply side of valve 61 exceeds the pressure in the chamber, this valve is moved into the position shown in dotted lines, and the liquid then moving with considerable velocity in the discharge pipe draws in liquid through valve 50 to follow it. In the meantime the liquid oscillates between the liquid supply tank 62 and chamber 1 expelling burnt products from the chamber and drawing in a fresh combustible charge.

pressing air in chamber 3, some of such compressed air being delivered from the apparatus and some being retained to form the necessary elastic cushion to produce the reverse flow of liquid. When this reverse flow occurs, valves 50 and 51 are both shut and the energy of expansion of the elastic cushion in chamber 3 is utilized to compress the combustible charge in chamber 1 and to draw a fresh charge of air into chamber 3.

When relatively low pressures are wanted, instead of valve 50 being normally closed and valve 51 open, valve 50 is normally open and valve 51 is normally closed, and the effect of this arrangement has already been described.

For the sake of simplicity a tank has been shown extending across the inlets of valves 50 and 51, but it is found advantageous to place a partition in the tank such that the liquid must flow a considerable distance in passing between that portion of the tank which communicates with valve 50 and that portion which communicates with valve 51. Thus a large eifective cooling surface can be obtained. The arrangement is practically equivalent to two tanks connected together at their ends.

So far only one pump and one air vessel, fitted with valves, have been described in combination to produce the complete air compressor, but it is evident that either or both parts of the apparatus may be multiplied to produce a single combination. Also, when the energy of combustion is delivered to more than one air vessel only one air vessel need be used for actually delivering air from the apparatus. Take, for instance, the combination of one pump, one air vessel fitted with valves, and one plain air vessel such as is shown in Fig. 8. Then l the energy of combustion in chamber 1 may be utilized to compress and discharge air from chamber 3 and to store energy for producing the return flow in air vessel 63. Again in such a combination of parts the air vessel 63 may be utilized to absorb the greater part of the energy of combustion developed in chamber 1 and thus store energy which produces the return flow to compress air in and deliver air from chamher 3 and to compress a fresh combustible charge in chamber 1. In the latter case the liquid duct connecting chambers 1 and 3 rest.

would be comparatively short and the liquid duct connecting air vessel 63 would be relatively long.

The operation in the last mentioned case may be explained with reference to Fig. 8. Assmning, for the sake of example, that the pump is of the type described in said 00- pending application having Serial No. 438,425, in which liquid oscillates between the supply tank and the combustion chamber to expel the burnt gases and to take in a fresh combustible charge. At the beginning of a cycle all the valves are in the position shown, and in the top of chamber 1 there is a compressed combustible charge, and in the top of chamber 3 a small compressed elastic cushion, both chambers being in great part filled with liquid, while in air vessel 63 there is a charge of air with the liquid at a low level. Ignition occurs in chamber 1 and liquid is driven downward and outward from the chamber toward air vessel 63 compressing the air in this vessel and incidentally further compressing the elastic cushion in chamber 3, which later 011 expands again. Air vessel 63 must be large enough to provide suilicient elastic cushion to permit the following actionz l Vhen expansion in chamber 1 has reached a point at which valve 64 opens, liquid from the supply ($2 enters this chamber and gives the exhaust and charging stroke therein while in chamber 3 the level of the liquid falls consequent upon the pressure being reduced, and a charge of air is drawn into this chamber. The spring on valve 6% is adjusted so that the valve remains open during the first part of the return flow due to expansion of the compressed air in vessel 63, but as the velocity of the liquid increases valve Bl shuts under its action, the adjustment being such that the quantity of liquid which enters and leaves through this valve at each cycle is the same. The intlowing liquid is now forced to rise in chambers 1 and 3 compress ing the fresh combustible charge in 1 and air in 3. vVhenthe pressure in chamber 3 is suilicient, valve 15' is opened and air is discharged until the kinetic energy of the liquid is expended and the liquid comes to Valve 15'then shuts, and everything is ready for ignition in chamber 1 and repetition of the cycle.

It should be mentioned that when ignition occurs in chamber 1 the level of the liquid in chamber 3 may either" be above or below the level of the air discharge pipe in chamber 3. If it is above, valve 16 has already been shut by the rising liquid, and consequently the increased pres sure in chamber. 11 merely compresses the cushion in the top of chamber 3 as stated, but it the level was below, there will be a further discharge of air from chamber 3 until the liquid rising shuts valve 16 in the manner already described with refer ence to other cases.

The arrangement mentioned in the last paragraph may be modified by fitting a valve for liquid close to air vessel 63 in the pipe which connects this air vessel with the chambers, in which case it is unnecessary that the liquid which enters and leaves at valve Gl at each cycle should be the same in amount, and the operations may more nearly resemble that described in connection with Fig. 7, where there are two valves for liquid.

The possible combinations of different types of pumps, one or more air compressor chambers and one or more air vessels, with and without liquid inlet valve, are too many for even an enumeration of them, and the manner in which they operate is materially altered by altering their relative positions and the lengths of the ducts which join them, but as the principles in volved are common to all of them the examples given will serve to illustrate the invention. It may, however, be advisable to mention the case in which there is a rapid movement of liquid between the combustion chamber and the air vessel, and Fig. 9 illustrates this modification.

There may be merely a short length 01 pipe connecting separate pump and air compressor portions, this pipe being continued to a considerable length to join an air vessel, or the pump and the air compressor portions may be combined as shown in Fig. 9. In this case the compressor chamber 3 is contained within the com bustion chamber 1 and is titted with the usual inlet valve 14 and outlet valve 15 but inaddition to the latter there is a second air outlet valve 65 rigidly connected through rod 66 to valve 67, the rod being continued into a guide 68 and carrying a fixed collar 69. Between this collar and the guide is a spring 70 tending to urge the two valves upward, and the length of the rod between valves 65 and 67 is such that these 'alve's cannot both be closed at the same time. As in the previous case pipe st connects with an air vessel 63 which serves to store the energy for reversing the flow of: liquid, but a rising main with an open top would also serve a similar purpose.

Assuming the cycle to start with a compressed combustible charge in the top of chamber 1, and a charge of air compressed to the same compression pressure in chamber 3, and that a charge of air exists in chamber 63, all the valves being in the position shown, ignition occurs, and under the increased pressure there is a rapid movement of liquid past valve 67 between chambers 1 and 3 tending to equalize the pressures therein, but owing to the kinetic sure in chamber 1, so that a reverse flow starts again. Owing to the excess of pressure in chamber 3, the rapid movement of the liquid, and the fact that valve 67 is of greater area than valve 65, valve 67 is closed on its seat against the action of spring and this movement opens valve 65 and so permits a portion of the air compressed in the top of chamber 3 to escape The pressure in chamber rod 66 thus opening valve 67 and closing valve 65.

There are now in chamber 1 partly expanded products of combustion and in chamber 3 a portion of the compressed air charge,

and these two continue to exert pressure on the liquid driving it outward along pipe i so that liquid rises in air vessel 63 and compresses air therein, thus storing the energy for the reverse flow. Theliquid continues to move, owing to its kinetic energy, after the products of combustion, and the air in chamber 3, have expanded to atmosphere, and its further downward movement causes valve 14: to open and a charge of air to be drawn in, after which valve 14 closes again. The liquid, having come to rest, returns under the influence of the compressed air in air vessel 63 and expels products of 001m bustion from chamber 1 through, exhaust valve 6 until, the level of this valve having been reached, the liquid shuts it by impact, a small cushion of exhaustproducts being imprisoned to prevent shoc'r. Liquid now rises in chamber 3, compressmg the air con tained therein, until the liquid is brought to rest. The pressure in chamber 3 is now greater than the pressure in air vessel 63 and. a movement of liquid toward the air vessel again takes place. When the air in chamber 3 has expanded nearly to atmosphere the liquid in chamber 1, being higher than in chamber 3, falls and draws in a fresh combustible charge. Again the liquid comes to rest, and the energy of the compressed air in the air vessel produces a flow of liquid toward chambers 1 and 3, compressing the fresh combustible charge in chamber 1 and the charge of air in chamber 3 in readiness for the starting of a fresh cycle by the ignition of the charge in chamber 1.

The apparatus last described will work without valves 65 and 67, the usual valve fittings only being provided, like those shown in Fig. 8. In fact, the object of valves 65 and 67 is to prevent liquid being ejected with the air when the surface of the liquid in chamber 3 is disturbed by the sudden fiow from chamber 1 to chamber 3 at the moment of ignition. WVhen working without these valves, air is allowed to escape from chamber 3 at the first part of the cycle, until either the pressure in chamber 3 no longer exceeds that at which the air is de livered, or until the usual valve 16, described in connection with other figures and now substituted for valve 65, isshut by impact of liquid. The partly expanded products of combustion in chamber 1 and the compressed air which has not escaped from chamber 3 then act together in driving the liquid outward toward air vessel 63 and the rest of the cycle is the same as that last described.

In this, as in other cases, any other type of pump described in the aforesaid specifications may be used. but it is unnecessary to describe the modifications of the. cycle which would be introduced by so doing.

Where no fresh liquid is introduced a measured combustible charge is preferably used and the quantity of air which is allowed to enter the compressor at each cycle mav also be measured and limited in amount.

For some purposes it is allowable that the compressed air delivered from the apparatus should be mixed with products of combustion, as for instance, when the compressed air is to be used for driving a motor, and when this is the case the pump and the compressor may be interchangeable in respect to their functions, so that combustion occurs in each alternately. Such an arrangement is shown in Fig. 17 where 113 and 114 are the chambers which serve alternately as combustion chambers and air compressor chambers. In the top of chamber 113 are fitted an inlet valve 115 for combustible mixture, an inlet valve 117 for air, and an'exhaust valve 119 for the delivery of a mixture of compressed air and burnt products. Corresponding parts 116, 118 and 120 are fitted in the top of chamber 114. Rigidly attached to the top casting of chamber 113 are pivots 121 and 122 about which move two 3-arm cranks 125 and 126. Theleft and right hand arms.

are adapted to engage with pins fitted to the stems or valves 115,117 and 119 as shown in the figure. The top arm of crank 125 is attached by springs 129 and 130 to pawls 131 and 132 respectively, and these pawls are connected by rod 133. The top arm of crank 126 is connected by springs 13 1 and 135 with pawls 136 and 137 respectively, which are connected by rod 138. Pawl 131 is adapted to engage under a collar 139 on the stem of valve 115. Pawls 132 and 136 are adapted to engage under the collar 140 on the stem of valve 117 and pawl 137 is adapted to engage under the collar 141 on the stem of valve 119. In the outlet pipe there is, in addition to valve 119 a springcontrolled valve 142. Corresponding parts are fitted to the top of chamber 11. 1.

'The action of the apparatus is as fol lows :The illustrated position of the valves is correct for that part of the cycle in which there is a compressed combustible charge in the top of chamber 113 and a charge of air and burnt products in chamber 114. Ignition now occurs in chamber 113 and the liquid is forced downward and outward from this chamber and rises in chamber 114 expelling the mixed charge at the desired pressure past valves 120 and into'the outlet pipe 157. After the liquid has attained the level of the inwardly extending pipe 152 it rises in this pipe and shuts valve 120 by impact. This valve is at once locked by pawl 1.44 engaging under collar 145 and simultaneously pawl 146 is released from under collar 147, this motion being obtained by the tension on spring 149 which, in the position shown, is greater than the tension on spring 148. The further rise of the liquid in chamber 114 compresses the elastic cushion in the top thereof and stores the energy to give the reverse flow. When the combustible products in chamber 113 have expanded to atmospheric pressure valve 117 is sucked open and air is drawn in to mix with the products of combustion and this motion ,of the valve moves cranks 125 and 126 through pin 150 engaging with them. When the suction stroke in chamber 113 is finished and the liquid comes to rest, valve 117 closes under the action of its spring and pawls 132 and 136 engage under its collar and pawls 131 and 137 are disengaged from under collars 139 and 141 respectively, this movement being brought about by the fact that in the new position of cranks 125 and 126 the tension of springs 129 and 135 is in creased and that of springs 130 and 134 diminished. Valve 119 being now released falls by its own weight, and when the energy stored in the elastic cushion in the top of chamber 114 causes the reverse How the liquid rising in chamber 113 has a large volume to compress and will not reach the level of the bottom of pipe 151; nothing happens therefore in this chamber except the compression of the mixture therein. But in chamber 114 when the pressure has fallen to atmosphere the further movement draws in a combustible charge past valve 116 and the movement of this valve, causing pin 153 to engage against crank 127, changes the position of this crank and when the valve shuts again under action of its spring pawl 154 engages under collar 155 and locks the valve, while pawl 156 is withdrawn from under col.- lar 147. The liquid having again come to rest and the pressure in chamber 113 being higher than inchamber 114, a second outward flow occurs from chamber 113 and the combustible charge is compressed in chamber 114 and the ignition of this charge starts a fresh cycle in which the functions of the chambers are reversed. Springs, not shown,

areused to render stable the extreme positions of cranks 125, 126, 127 and 128 in the manner already referred to for other similar cases. Preferably a measured charge of combustible mixture is used.

Mention has been made of an arrangement in which the pump may be simultaneously working to raise water and to compress air, and such an arrangement is shown in Fig. 10 where 1 is a pump, 3 is the air compressor and 71 is an air vessel from which there is a delivery pipe to an elevated reservoir, in this case shown as an open top tank. The pump may be either of the type which has one outward movement of liquid and one in ward movement of liquid in pipe 4 per cycle, or the type in which there are two movements of each kind per cycle. If the former, then during the expansion of the ignited combustible mixture liquid is driven along pipe 4 and rises into the air compressor chamber 3, compresses the air therein and delivers some of this air under pressure until the liquid, having risen far enough, valve 16 is shut so that there can be no further delivery of air. The outlet being closed, pressure continues to rise until valve 72, which is an ordinary non-return valve fitted in the bottom of air vessel 71, opens, and the rest of the kinetic energy of the moving liquid is expended in forcing liquid into this air vessel and so causing liquid to be delivered into the elevated tank until the liquid comes to rest, when valve 72 closes. There is then energy left in the elastic cushion of air in the top of chamber 3, which reverses the flow and gives the compression stroke in chamber 1, and when the cushion in chamber 3 has expanded to atmosphere a fresh charge of air is drawn into this chamber. When the liquid again ceases to move there is a fresh combustible charge in the top of chamber 1, the ignition of which starts a fresh cycle. Of course, there is an inflow of liquid at each cycle from the low level tank 62, but there is no necessity to repeat the cycle of operations for the pump as such.

If the pump is of the type in which there are four strokes per cycle, then the action may be regarded the same as that just de-' scribed until the reverse flow occurs, when the liquid rising in chamber 1 expels products of combustion until it reaches the level of the exhaust valve, which it shuts, and the compression of the elastic cushion follows. As the liquid falls in chamber 3, after the pressure reaches atmosphere, an intake of the air occurs and when the elastic cushion in chamber 1 expands and gives a reverse flow a combustible charge is taken into chamber 1 and the charge of air in chamber 3 is compressed until the liquid again comes to rest; the flow is once more reversed and the fresh combustible charge is compressed in chamber 1 ready for starting a fresh cycle.

Fig. 10 also indicates that the level of the pump portion and the compressor portion need not be the same; indeed, the latter may be either above or below the pump portion. 11 it is above the pump portion then the height of liquid in the compressor portion assists the elastic cushion in bringing about a reverse flow, while on the other hand, if the compressor portion is below the pump portion the energy stored in the elastic cushion must be greater in order to overcome the difference in level of the liquid in the two chambers.

That the eiiective mass oi": liquid'that is to have reciprocating movement in the app aratus may be varied by altering the effective length of the pipe which connects the pump portion to the compressor portion, has already been mentioned, and such an arrangement is shown in plan in Fig. 11. 1 and 3 are respectively the pump and the compressor chambers and the valves for liquid are shown at 50 and 51. In pipe 4 are fitted two valves 73 and 74 and in cross connecting pipes are situated valves 75 and 76. If valves 75 and 76 are shut and valves 73 and 74 are open, the whole length of pipe 4 is effective. If valves 73 and 76 are open and valves 74 and 75 are shut it is equivalent to cutting off that portion of the pipe which lies to the right of valve 76. When valves 73 and 76 are shut and valve 75 is open it is equivalent to cutting oii that portion of the pipe which lies to the right of valve 75. There may be more cross connections and valves if it is desired to have a greater number of variations of efiective length of pipe. Thus, by simply opening and closing valves the effective length of the pipe may be varied in any desired manner.

it has been assumed, in describing the cycles of the various modifications of apparatus, that there already existed a pressure in the outlet pipe at the compressor portion on the discharge side of the outlet valve equal to that at which it was desired to deliver the compressed air. This may, however, not be the case in starting the apparatus, as for instance, when a reservoir for containing the compressed air delivered has to be pumped up to the desired pressure. If the compressor started without pressure in the delivery pipe the irregular working which would otherwise result until the desired pressure had been attained may be avoided by fitting to the outlet pipe the simple device shown in Fig. 12. A movable piston 77 is held in position in a cylinder 78 by two springs 79 and 80 and on the top side of the piston air is maintained at atmospheric pressure by holes 81 which communicate with the atmosphere, the piston is subject to the pressure of the air in the delivery pipe 82. The piston is shown inthe position which it has when while the under side of there is atmospheric pressure in the pipe 82, and in this position spring 79 has moved piston 77 into its lowest position and has compressed spring 80 to such an extent that it requires a pressure below the outlet valve 15 equivalent to the desired pressure at which air is to be delivered to open this valve. As theair compressor is set to work and air is discharged past valve 15 the pressure in pipe 82 begins to rise and the pressure on the under side of the piston gradually increases until the desired working pressure for the compressed air is reached when piston 77 has been moved upward against the pressure of spring 7 9. This upward movement relieves the pressure on spring 80 and the springs may be so adjusted that little or no compression now remains in .spring 80. Conse quently valve 15 now opens when the pressure below it is substantially equal to the pressure at which the air is to be delivered. By this arrangement the pressure at which valve 15 opens may be maintained practically constant from the starting of the apparatus until the desired pressure of delivery is attained, and thus the pressure conditions for eachcycle remain the same, in spite of the varying pressure at the delivery side 01" the outlet valve.

A device for measuring a combustible charge into the combustion chamber of the pump hasalready been alluded to, and a further description of it will now be given in connection with Fig. 13.

The combustion chamber 1 is fitted with the usual inlet valve 5, but the stem of this valve has a connection shown diagrammatically as a rod 83 with the stem of valve 84 placed in the combustible inlet pipe, such thatwhen valve 5 opens valve 84 is closed. The combustible inlet pipe 87 is also connected with a measuring chamber 85 in the top of which there is a valve 86 adapted to be shut by impact of liquid upon it. Measuring chamber 85 is connected with a supply of water which is open to the atmosphere in such a manner, for instance, as is shown in Fig. 14 and so that the normal level of water in the measuring chamber may be adjusted.

The action of the apparatus is as follows When valve 5 opens, valve 84 is closed and the suction in chamber 85 causes the liquid to rise therein until valve 86 shuts by the impact of liquid upon it. Thus, valves 84 and 86 being both closed, no more combustible mixture can be taken into chamber 1 and when the pressure in this chamber and in the combustible inlet pipe 87 has-risen sufliciently, valve 5 will shut under the action of its spring. This movement of valve 5 opens valve 84, and further combustible mixture flows into pipe 87. Valve 86 falls by its own weight, and the liquid in chamber 85,

in falling to its normal level draws a measured quantity of combustible mixture into the chamber.

The seats of valves 5 and 84: are prolonged in such a manner as to cause these valves to act partly as piston valves, so that valve 8% may be shut by the time valve open.

It will be seen that by altering the normal level of liquid in chamber 85, the quantity of the measuredcharge taken in can be varied.

In order to keep the pressure of the compressed air approximately constant it is necessary to make the apparatus deliver more or less air under such pressure to meet the greater or reduced demand for the supply of compressed air. One way of accomplishing this is to cause the amount of measured combustible charge which enters the combustion chamber at each cycle to be increased or diminished according to the amount of compressed air required, and in Fig. 1 1 a simple arrangement for doing this is shown, Chamber 3 on the right of the figure is the usual air compressor chamber fitted with the usual valves, and at a branch on the compressed air outlet pipe there is fitted a cylinder 88 containing a piston 89 controlled by a spring 90. Attached to the piston is a rod 91 carrying a pin 92 which engages in the slotted end of bell crank 93 and, by means of link 94, bell crank 95, connecting link 96 and arm 97, can rotate valves 98 and 99. Valve 98 is fitted in a water supply pipe 100 and valve 99 is fitted in a run off pipe 101 in such a way that when valve 98 is opened water will be supplied into tank 102 to raise the level of water therein and when valve 99 is open water will be allowed to run from tank 102 so as to lower the level of water therein. Assuming that the pressure of the air in pipe 82 is that at which the compressed air is to be delivered, and which is to be kept approximately constant in spite of varying demands, then piston 89 will be held in equilibrium by the pressure of air above it and by the action of the spring 90 below it, and in this position valves 98 and 99 are both shut so that the normal level of liquid in tank 102 and measuring chamber 85 remains unaltered. Now

suppose that owing to an increased demand the pressure in pipe 82 falls, then spring 90 moves the piston 89 upward and by means of the gear shown valve 98 is further shut and valve 99 opened so that water may now escape from tank 102 lowering the level of water therein. The effect of this is that a larger combustible charge is drawn into the measuring chamber and so passed at each cycle into the combustion chamber, and the energy output per ci cle is thus increased. More compressed air is consequently delivered at each cycle to meet the increased demand. Whenthe demand for compressed air falls so that the pressure in outlet pipe 82 increases, the action of the parts is reversed and more water enters the tank 102 to raise the level therein, whereby a smaller measured charge passes into the combustion chamber at each cycle, and less work is done.

The elfect of more or less liquid in an apparatus such as is illustrated in Figs. 1 to at, where there'is no intake of fresh liquid at each cycle, has already been mentioned, and by reducing this quantity of liquid the amount of combustible charge and the amount of compressed air delivered or either of these may be increased, while with more liquid in the apparatus the reverse may be the case. If the energ 7 derived from each consecutive combustible charge is constant and if the pressure of the air in the outlet pipe of the compressor diminishes, then one effect will be that the maximum cushion pressure in the air compressor chamber will increase, and on the other hand, if the pressure of the compressed air in the outlet pipe increases, the maximum cushion pressure will be decreased. This variation of the cushion pressure arising from the above or any other cause may be applied to give a governing effect on the apparatus by varying the quantity of oscillating liquid so as to keep the cushion pressure approximately constant in spite of vary ing conditions. One simple form of apparatus suitable for this purpose is shown in Fig. 14, where 108 is an air vessel, high level tank, or other device for storing liquid under pressure, connected with chamber 3 through a pipe 104: which dips to such a level in the chamber that the open end of the pipe is always below the surface of the liquid. A piston valve 105 moves in a cylinder 106 so as to control communication between the air vessel 103 and the pipe 10% giving more or less passage according to its position. One end of the cylinder 106 is open to the chamber 3 so that the pressure in the chamber is communicated to one end of the valve 105 and acting upon the other end of the valve is a spring 107 the thrust of which can be adjusted by a screw. Assuming, in the first place, that valve 105 is fixed in such a position that a throttled com munication is established between vessel 103 and chamber 8, liquid flows past valve 105, such flow being determined in direction and amount by the difference of pressure existing between chamber 3 and vessel 103. The pressure or head in vessel 103 may be ad justed so that for a given set of conditions the amount of liquid which passes from chamber 3 to the vessel, during those portions of the cycle when the pressure in chamber 3 is higher than the pressure in the vessel, may equal the amount of liquid which 

